A method for automatically determining the rectum distance in the colon is known from the European patent specification EP 1 057 161 B1. It is described there how it is possible by automatically determining a path in 3D image data records of colon displays, to determine the path between a lesion in the colon and the rectum. Reference is also made by way of example to the use of the Dijkstra method for finding the shortest path on a graph.
The problem with such methods in which the path calculation is carried out automatically from a 3D display of a patient's colon resides in the fact that, depending on the position in which the 3D display is recorded, parts of the colon cannot be completely continuous. Consequently, the automatic method cannot lead to the goal in the case of such displays, but must be stopped prematurely.